Device including electrode having thickness to facilitate tracking

ABSTRACT

Devices are described herein that include an electrode having a thickness to, among other things, facilitate tracking. For example, the thickness of an electrode that is included in a device may be configured to cause a midpoint of a projection of the electrode on a sensor matrix to track a point on the device (or on a portion thereof, such as the electrode) that is closest to the sensor matrix. In another example, the thickness may be configured to cause a location of the electrode that is detected by the sensor matrix to track a point on the device (or on a portion thereof, such as the electrode) that is closest to the sensor matrix.

BACKGROUND

Computing devices (e.g., tablet computers, personal digital assistants)often include touch screens that enable the computing devices to detecttouch commands and/or hover commands. For instance, a touch screen mayinclude any of a variety of materials that are responsive to resistance,capacitance, and/or light for enabling detection of such commands. Atouch screen usually includes a sensor matrix, which includes an arrayof row sensors and an array of column sensors. Each of the sensors inthe arrays is typically configured to detect an object when the objectis placed within a certain proximity to the sensor. For instance, anamount of resistance, capacitance, and/or light detected by the sensormay indicate whether the object is proximate the sensor. A location ofthe object with respect to the touch screen may be determined based onthe amount(s) of resistance, capacitance, and/or light that are detectedby one or more of the sensors.

A stylus is an object that is commonly used to provide input to a touchscreen. For instance, the stylus may be used to write a message on thetouch screen and/or to select icons that are displayed on the touchscreen. It is desirable for a detected location of the stylus to be asclose as possible to the physical location at which the stylus istouching the touch screen or being used to point at the touch screen.However, in practice, the detected location differs from the physicallocation, and the difference (referred to as the position error)typically increases when the stylus is tilted from a position that isnormal (i.e., perpendicular) to the touch screen.

SUMMARY

Various devices are described herein that include an electrode having athickness to, among other things, facilitate tracking. For example, thethickness of an electrode that is included in a device may be configuredto cause a midpoint of a projection of the electrode on a sensor matrixto track a point on the device (or on a portion thereof, such as theelectrode) that is closest to the sensor matrix. In another example, thethickness may be configured to cause a location of the electrode that isdetected by the sensor matrix to track a point on the device (or on aportion thereof, such as the electrode) that is closest to the sensormatrix.

A first example device includes a member and an electrode. The memberhas a proximal end and a distal end at opposing ends of an axis. Theelectrode is positioned at a designated end of the member. Thedesignated end is the proximal end or the distal end. The electrode isconfigured to provide a signal to a sensor matrix of a computing devicein response to the electrode being placed proximate the sensor matrix.The electrode has a thickness along the axis. The thickness isconfigured to cause a midpoint of a projection of the electrode on thesensor matrix to track a point on the electrode or on the device as awhole that is closest to the sensor matrix as the member is rotated froma first position in which the member is orthogonal to the sensor matrixto a second position in which the member is non-orthogonal to the sensormatrix.

A second example device includes a member and an electrode. The memberhas a proximal end and a distal end at opposing ends of an axis. Theelectrode is positioned at a designated end of the member. Thedesignated end is the proximal end or the distal end. The electrode isconfigured to provide a signal to a sensor matrix of a computing devicein response to the electrode being placed proximate the sensor matrix.The electrode has a thickness along the axis. The thickness isconfigured to cause a location of the electrode that is detected by thesensor matrix to track a point on the electrode or on the device as awhole that is closest to the sensor matrix as the member is rotated froma first position in which the member is orthogonal to the sensor matrixto a second position in which the member is non-orthogonal to the sensormatrix.

A third example device includes an elongated member, a driver circuit,and a module. The elongated member extends along an axis. The drivercircuit is configured to generate an active signal. The module iscoupled to an end of the elongated member. The module includes anelectrode that is configured to provide the active signalelectrostatically to a sensor matrix of a computing device. Theelectrode has a thickness along the axis. The thickness is configured tocause a midpoint of a projection of the electrode on the sensor matrixto track a point on the electrode, on the module, or on the device as awhole that is closest to the sensor matrix as the elongated member isrotated from a first position in which the elongated member isorthogonal to the sensor matrix to a second position in which theelongated member is non-orthogonal to the sensor matrix.

A fourth example device includes an elongated member, a driver circuit,and a module. The elongated member extends along an axis. The drivercircuit is configured to generate an active signal. The module iscoupled to an end of the elongated member. The module includes anelectrode that is configured to provide the active signalelectrostatically to a sensor matrix of a computing device. Theelectrode has a thickness along the axis. The thickness is configured tocause a location of the module that is detected by the sensor matrix totrack a point on the electrode, on the module, or on the device as awhole that is closest to the sensor matrix as the elongated member isrotated from a first position in which the elongated member isorthogonal to the sensor matrix to a second position in which theelongated member is non-orthogonal to the sensor matrix.

This Summary is provided to introduce a selection of concepts in asimplified form that are further described below in the DetailedDescription. This Summary is not intended to identify key features oressential features of the claimed subject matter, nor is it intended tobe used to limit the scope of the claimed subject matter. Moreover, itis noted that the invention is not limited to the specific embodimentsdescribed in the Detailed Description and/or other sections of thisdocument. Such embodiments are presented herein for illustrativepurposes only. Additional embodiments will be apparent to personsskilled in the relevant art(s) based on the teachings contained herein.

BRIEF DESCRIPTION OF THE DRAWINGS/FIGURES

The accompanying drawings, which are incorporated herein and form partof the specification, illustrate embodiments of the present inventionand, together with the description, further serve to explain theprinciples involved and to enable a person skilled in the relevantart(s) to make and use the disclosed technologies.

FIG. 1 is a perspective view of an example system that includes acomputing device and an input device including a writing electrodehaving a thickness to facilitate tracking in accordance with anembodiment.

FIG. 2 is a perspective view of an example system that includes acomputing device and an input device including an eraser electrodehaving a thickness to facilitate tracking in accordance with anembodiment.

FIG. 3 is a block diagram of an example computing device that includes asensor matrix in accordance with an embodiment.

FIG. 4 is a diagram of an example device that includes a writingelectrode having a thickness to facilitate tracking in accordance withan embodiment.

FIG. 5 is a diagram of an example device that includes an eraserelectrode having a thickness to facilitate tracking in accordance withan embodiment.

FIG. 6 is a diagram of an example device that includes a writingelectrode having a first thickness and an eraser electrode having asecond thickness to facilitate tracking in accordance with anembodiment.

FIG. 7 is diagram of another example device that includes an eraserelectrode having a thickness to facilitate tracking in accordance withan embodiment.

The features and advantages of the disclosed technologies will becomemore apparent from the detailed description set forth below when takenin conjunction with the drawings, in which like reference charactersidentify corresponding elements throughout. In the drawings, likereference numbers generally indicate identical, functionally similar,and/or structurally similar elements. The drawing in which an elementfirst appears is indicated by the leftmost digit(s) in the correspondingreference number.

DETAILED DESCRIPTION I. Introduction

The following detailed description refers to the accompanying drawingsthat illustrate exemplary embodiments of the present invention. However,the scope of the present invention is not limited to these embodiments,but is instead defined by the appended claims. Thus, embodiments beyondthose shown in the accompanying drawings, such as modified versions ofthe illustrated embodiments, may nevertheless be encompassed by thepresent invention.

References in the specification to “one embodiment,” “an embodiment,”“an example embodiment,” or the like, indicate that the embodimentdescribed may include a particular feature, structure, orcharacteristic, but every embodiment may not necessarily include theparticular feature, structure, or characteristic. Moreover, such phrasesare not necessarily referring to the same embodiment. Furthermore, whena particular feature, structure, or characteristic is described inconnection with an embodiment, it is submitted that it is within theknowledge of one skilled in the relevant art(s) to implement suchfeature, structure, or characteristic in connection with otherembodiments whether or not explicitly described.

II. Example Embodiments

Example devices described herein include an electrode having a thicknessthat is capable of facilitating tracking. For example, the thickness ofan electrode that is included in a device may be configured to cause amidpoint of a projection of the electrode on a sensor matrix to track apoint on the device (or on a portion thereof, such as the electrode)that is closest to the sensor matrix. In another example, the thicknessmay be configured to cause a location of the electrode that is detectedby the sensor matrix to track a point on the device (or on a portionthereof, such as the electrode) that is closest to the sensor matrix.For instance, the location of the electrode that is detected by thesensor matrix may be a centroid of the electrode.

Example devices described herein have a variety of benefits as comparedto conventional devices for providing input to a computing device. Forinstance, an example device may be capable of increasing an accuracywith which a computing device is capable of determining a physicallocation of the device or a portion thereof (e.g., a point on the deviceor the portion thereof that is closest to a sensor matrix). Theincreased accuracy may reduce a difference between the physical locationand a detected location of the device that is calculated by thecomputing device. An electrode having a thickness as described hereinmay appear more symmetrical to the computing device than a conventionalelectrode. Including an electrode having a thickness as described hereinin a device may eliminate a need for relatively complex and/or costlymechanisms for calculating a tilt of the device.

FIG. 1 is a perspective view of an example system 100 in accordance withan embodiment. The system 100 includes a computing device 102 and aninput device 104. The computing device 102 is a processing system thatis capable of receiving input from the input device 104. An example of aprocessing system is a system that includes at least one processor thatis capable of manipulating data in accordance with a set ofinstructions. For instance, a processing system may be a computer (e.g.,a tablet computer, a laptop computer, or a desktop computer), or apersonal digital assistant.

The computing device 102 includes a display 106, processor(s) 112, amemory 114, a transmit circuit 116, and a receive circuit 118. Thedisplay 106 is configured to be a touch screen. Touch and/or hoverfunctionality of the display 106 is enabled by the receive circuit 118,which is capable of sensing objects that are placed proximate thedisplay 106. For example, the receive circuit 118 may sense a locationat which an object physically touches the display 106. In accordancewith this example, no space is between the object and the display 106.In another example, the receive circuit 118 may sense a location atwhich an object hovers over the display 106. In accordance with thisexample, the object and the display 106 are spaced apart and do nottouch. The receive circuit 118 receives input from such objects viaactive or passive signals at locations on the display 106 thatcorrespond to locations of the objects. The display 106 includes pixelshaving characteristics that are capable of being modified in response toreceipt of such input at the locations on the display 106 thatcorrespond to the pixels.

The processor(s) 112 are capable of performing operations based oninstructions that are stored in the memory 114 (e.g., in response toreceipt of input from the input device 104). For instance, theprocessor(s) 112 are configured to determine a location of a writingelectrode 108, which is included in the input device 104, based on inputthat is received by the receive circuit 118 from the input device 104.The processor(s) 112 are capable of modifying one or morecharacteristics of the pixels in the display 106 in response to suchinput. As shown in FIG. 1, the processor(s) 112 have caused writing 110to be displayed on the display 106 by changing characteristic(s) of thecorresponding pixels in the display 106. More particularly, theprocessor(s) 112 have caused the word “Hello” to be displayed on thedisplay 106 in response to the writing electrode 108 of the input device104 tracing the word “Hello” along a path that is proximate the display106.

The memory 114 stores computer-readable instructions that are executableby the processor(s) 112 to perform operations. The memory 114 mayinclude any suitable type of memory, including but not limited to readonly memory (ROM), random access memory (RAM), or flash memory.

The transmit circuit 116 is configured to generate a signal (e.g., atime-varying signal) for transmission to the input device 104. Forexample, the transmit circuit 116 may transmit the signal to the inputdevice 104 in anticipation of a response from the input device 104. Inaccordance with this example, if the writing electrode 108 is configuredto be a passive slug, the signal that is transmitted by the transmitcircuit 116 may be a time-varying voltage, and the response from theinput device 104 may be a time-varying current that is generated basedon a capacitance between the display 106 and the writing electrode 108.A passive slug is conductive material via which active signals are nottransmitted. Rather, passive signals may be transmitted via a passiveslug. For instance, the passive slug may respond to signal(s) that arereceived from the transmit circuit 116 by providing passive signal(s)that are based on the received signal(s).

The input device 104 includes the aforementioned writing electrode 108,a transmit circuit 120, a receive circuit 122, and processor(s) 124. Thewriting electrode 108 is electrically conductive and has a thickness, T,to facilitate tracking. For instance, the thickness, T, may enable thecomputing device 102 to more accurately track the writing electrode 108or a portion thereof (e.g., an edge of the writing electrode 108 that isclosest to the display 106) when the input device 104 is tilted from aposition that is normal to the display 106. Accordingly, the thickness,T, may be configured to cause the location where writing is displayed onthe display 106 to more closely match the intended location of a user ofthe input device 104 (e.g., when the input device 104 is placed in atraditional writing position). In one example embodiment, the thickness,T, of the writing electrode 108 is configured to cause the perceivedlocation of the writing electrode 108 as determined by the processor(s)112 (i.e., the detected location of the writing electrode 108) to tracka point on the writing electrode that is closest to the display 106. Inanother example embodiment, the thickness, T, of the writing electrode108 is configured to cause a midpoint of a projection of the writingelectrode 108 on the display 106 to track a point on the writingelectrode 108 that is closest to the display 106. Further detailsregarding some embodiments in which a writing electrode has a thicknessto facilitate tracking are provided below with reference to FIGS. 4 and6.

The transmit circuit 120 is configured to transmit an input to thecomputing device 102 to cause the processor(s) 112 to determine alocation of the writing electrode 108. For example, the transmit circuit120 may transmit the input to the computing device 102 based on anindication from the processor(s) 124 that the input has been selected tobe provided to the computing device 102. In another example, thetransmit circuit 120 may generate the input (e.g., without beingprompted by the processor(s) 124).

The receive circuit 122 is configured to receive signals that aretransmitted by the transmit circuit 116 of the computing device 102. Forinstance, the receive circuit 122 may forward the signals to theprocessor(s) 124 for processing.

The processor(s) 124 are configured to process the signals that arereceived via the receive circuit 122. For instance, the processor(s) 124may select an input from a plurality of differing inputs to betransmitted to the computing device 102 based on signal(s) that arereceived from the transmit circuit 116 of the computing device 102.

It will be recognized that the system 100 may not include one or more ofthe display 106, the processor(s) 112, the memory 114, the transmitcircuit 116, the receive circuit 118, the transmit circuit 120, thereceive circuit 122, and/or the processor(s) 124. Furthermore, thesystem 100 may include components in addition to or in lieu of thedisplay 106, the processor(s) 112, the memory 114, the transmit circuit116, the receive circuit 118, the transmit circuit 120, the receivecircuit 122, and/or the processor(s) 124.

FIG. 2 is a perspective view of another example system 200 in accordancewith an embodiment. System 200 includes a computing device 202 and aninput device 204. The computing device 202 is a processing system thatis capable of receiving input from the input device 204. The computingdevice 202 includes a display 206, processor(s) 212, a memory 214, atransmit circuit 216, and a receive circuit 218, which operate in amanner similar to the processor(s) 112, the memory 114, the transmitcircuit 116, and the receive circuit 118 described above with referenceto FIG. 1.

For instance, the processor(s) 212 are capable of performing operationsbased on instructions that are stored in the memory 214 (e.g., inresponse to receipt of input from the input device 204). Theprocessor(s) 212 are configured to determine a location of an eraserelectrode 208, which is included in the input device 204, based on inputthat is received by the receive circuit 218 from the input device 204.The processor(s) 212 are capable of modifying one or morecharacteristics of the pixels in the display 206 in response to suchinput. As shown in FIG. 2, the processor(s) 212 have caused a portion ofwriting 210 to be erased on the display 206 by changingcharacteristic(s) of the corresponding pixels in the display 206. Moreparticularly, the processor(s) 212 have caused an erasure 226 to removea portion of the word “Hello” on the display 206 in response to theeraser electrode 208 of the input device 204 being moved along a paththat defines the erasure 226 while the eraser electrode 208 is proximatethe display 106.

The transmit circuit 216 is configured to generate a signal (e.g., atime-varying signal) for transmission to the input device 204. Forexample, the transmit circuit 216 may transmit the signal to the inputdevice 204 in anticipation of a response from the input device 204. Inaccordance with this example, if the eraser electrode 208 is configuredto be a passive slug, the signal that is transmitted by the transmitcircuit 216 may be a time-varying voltage, and the response from theinput device 204 may be a time-varying current that is generated basedon a capacitance between the display 206 and the eraser electrode 208.

The input device 204 includes the aforementioned eraser electrode 208, atransmit circuit 220, a receive circuit 222, and processor(s) 224. Theeraser electrode 208 is electrically conductive and has a thickness, T,to facilitate tracking. For instance, the thickness, T, may enable thecomputing device 202 to more accurately track the eraser electrode 208or a portion thereof (e.g., an edge of the eraser electrode 208 that isclosest to the display 206) when the input device 204 is tilted from aposition that is normal to the display 206. Accordingly, the thickness,T, may be configured to cause a location at which an erasure occurs onthe display 206 to more closely match the location that is intended by auser of the input device 204 (e.g., when the input device 204 is placedin a traditional erasing position). In one example embodiment, thethickness, T, of the eraser electrode 208 is configured to cause thedetected location of the eraser electrode 208 to track a point on theeraser electrode 208 that is closest to the display 206. In anotherexample embodiment, the thickness, T, of the eraser electrode 208 isconfigured to cause a midpoint of a projection of the eraser electrode208 on the display 206 to track a point on the eraser electrode 208 thatis closest to the display 206. Further details regarding someembodiments in which an eraser electrode has a thickness to facilitatetracking are provided below with reference to FIGS. 5-7.

The transmit circuit 220 is configured to transmit an input to thecomputing device 202 to cause the processor(s) 212 to determine alocation of the eraser electrode 208.

It will be recognized that the system 200 may not include one or more ofthe display 206, the processor(s) 212, the memory 214, the transmitcircuit 216, the receive circuit 218, the transmit circuit 220, thereceive circuit 222, and/or the processor(s) 224. Furthermore, thesystem 200 may include components in addition to or in lieu of thedisplay 206, the processor(s) 212, the memory 214, the transmit circuit216, the receive circuit 218, the transmit circuit 220, the receivecircuit 222, and/or the processor(s) 224.

FIG. 3 is a block diagram of an example computing device 300 inaccordance with an embodiment. The computing device 300 includes asensor matrix 328 and measurement logic 330. The sensor matrix 328includes a plurality of column electrodes 332A-332H and a plurality ofrow electrodes 334A-334K. The plurality of column electrodes 332A-332Hare arranged to be substantially parallel with a Y-axis, as shown inFIG. 3. The plurality of row electrodes 334A-334K are arranged to besubstantially parallel with an X-axis. The plurality of columnelectrodes 332A-332H are arranged to be substantially perpendicular tothe plurality of row electrodes 334A-334K. A first pitch, L1, betweenadjacent column electrodes 332A-332H indicates a distance between themidpoints of the adjacent column electrodes 332A-332H. A second pitch,L2, between adjacent row electrodes 334A-334K indicates a distancebetween the midpoints of the adjacent row electrodes 334A-334K. Thefirst pitch, L1, and the second pitch, L2, may be any suitable values.The first pitch, L1, and the second pitch, L2, may be same or different.For instance, the first pitch, L1, and/or the second pitch, L2, may beapproximately 2 mm, 3 mm, 4 mm, or 5 mm.

Placement of an object (e.g., the writing electrode 108 or the eraserelectrode 208) proximate a subset (e.g., one or more) of the columnelectrodes 332A-332H and a subset (e.g., one or more) of the rowelectrodes 334A-334K causes a change of capacitance to occur between theobject and the electrodes in those subsets. For instance, such placementof the object may cause the capacitance to increase from anon-measurable quantity to a measurable quantity. The change ofcapacitance between the object and each electrode in the subsets may beused to generate a “capacitance map,” which may correlate to a shape ofthe object. For instance, a relatively greater capacitance change mayindicate that a distance between the object and the correspondingelectrode is relatively small. A relatively lesser capacitance changemay indicate that a distance between the object and the correspondingelectrode is relatively large. Accordingly, a capacitance map, whichindicates capacitance changes associated with respective electrodes inthe subsets, may indicate the shape of the object.

In an example embodiment, placement of an object proximate the sensormatrix 328 at point A causes a first capacitance between the object andthe row electrode 334A to change, a second capacitance between theobject and the row electrode 334B to change, a third capacitance betweenthe object and the column electrode 332F to change, and a fourthcapacitance between the object and the column electrode 332G to change.It will be recognized that capacitances between the object and otherrespective electrodes may change, as well. For instance, thecapacitances between the object and those other respective electrodesmay change so long as the object is within a designated proximity (3 mm,5 mm, 7 mm, 10 mm, etc.) to those other electrodes. However, suchchanges would be less than the changes to the first, second, third, andfourth capacitances mentioned above due to the greater proximity of theobject to those other electrodes. Accordingly, the discussion will focuson the first, second, third, and fourth capacitances mentioned above forease of understanding.

The measurement logic 330 is configured to determine a location of anobject that is placed proximate the sensor matrix 328 based oncapacitance changes that are sensed by the plurality of columnelectrodes 332A-332H and the plurality of row electrodes 334A-334K orrespective subsets thereof. Accordingly, in the example embodimentmentioned above, the measurement logic 330 determines (e.g., estimates)the location, A, of the object based on the changes to the first,second, third, and fourth capacitances sensed at respective electrodes334A, 334B, 332F, and 332G. For instance, the measurement logic 330 mayestimate (X,Y) coordinates of the location, A.

Determining the location, A, of the object with an accuracy on the orderof the first pitch, L1, and/or the second pitch, L2, is relativelystraightforward. For instance, a location of a column electrode at whicha greatest capacitance change is sensed with respect to the object mayindicate (e.g., provide an estimate of) an X coordinate of the location,A. A location of a row electrode at which a greatest capacitance changeis sensed with respect to the object may indicate (e.g., provide anestimate of) a Y coordinate of the location, A.

One way to increase the accuracy of the estimate that is determined bythe measurement logic 330 is to decrease the first pitch, L1, betweenadjacent column electrodes 332A-332H and/or the second pitch, L2 betweenadjacent row electrodes 334A-334K. Another way to increase the accuracyis to interpolate (e.g., as a continuous function) the capacitancechanges that are sensed by the plurality of column electrodes 332A-332Hand the plurality of row electrodes 334A-334K or respective subsetsthereof. For instance, in accordance with the example embodimentmentioned above, the measurement logic 330 interpolates the changes tothe first, second, third, and fourth capacitances to determine thelocation, A.

FIG. 4 is a diagram of an example device 400 in accordance with anembodiment. The device 400 includes a member 440 and a writing electrode408. The member 440 has a proximal end, P, and a distal end, D, whichare at opposing ends of an axis 438. The member 440 may be a rigid bodythat contains circuitry for controlling writing functionality of thedevice 400, though the scope of the example embodiments is not limitedin this respect. The member 440 may have a size and/or a shape of aconventional writing pen or a conventional stylus, though the scope ofthe example embodiments is not limited in this respect. For instance,the member 440 may be approximately 150 mm long and approximately 10 mmin diameter or a different size and/or shape.

The writing electrode 408 is positioned at the proximal end, P, of themember 440. The writing electrode 408 is configured to provide a writesignal to a sensor matrix of a computing device in response to thewriting electrode 408 being placed proximate the sensor matrix. Thesensor matrix is represented by a line 428 for purposes of illustration.The writing electrode 408 has a thickness, T, along the axis 438.

As shown in FIG. 4, an orthogonal axis 436 is orthogonal to the sensormatrix 428. Accordingly, the member 440 is orthogonal to the sensormatrix 428 when an angle, θ, between the orthogonal axis 436 and theaxis 438 is zero. The member 440 is non-orthogonal to the sensor matrix428 when the angle, θ, between the orthogonal axis 436 and the axis 438is non-zero (e.g., greater than zero or less than zero).

A projection of the writing electrode 408 on the sensor matrix 428extends along the line 428 between points X1 and X2. A midpoint of theprojection of the writing electrode 408 on the sensor matrix 428 isrepresented by point XM. The midpoint, XM, is equidistant between thepoints X1 and X2. A point on the writing electrode 408 that is closestto the sensor matrix 428 is represented by point XL.

In a first example embodiment, the thickness, T, of the writingelectrode 408 is configured to cause the midpoint, XM, of the projectionof the writing electrode 408 on the sensor matrix 428 to track thepoint, XL, on the writing electrode 408 that is closest to the sensormatrix 428 as the member 440 is rotated from a first position in whichthe member 440 is orthogonal to the sensor matrix 428 to a secondposition in which the member 440 is non-orthogonal to the sensor matrix428. For instance, the midpoint, XM, may track the point, XL, as themember 440 is rotated about a first pivot point, which is defined as apoint on the writing electrode 408 that is closest to the sensor matrix428 when the member 440 is in the first position. It should be notedthat the angle, θ, is changing during the rotation of the member 440from the first position to the second position.

In one aspect of this embodiment, the thickness, T, of writing electrode408 may cause the midpoint, XM, of the projection to approximatelycoincide with the point, XL. For example, the thickness, T, may causethe midpoint, XM, to be within a distance from the point, XL, that is adesignated percentage of a diameter of the writing electrode 408 in aplane that is perpendicular to the axis 438. In accordance with thisexample, the thickness, T, may cause the midpoint, XM, to be within adistance from the point, XL, that is 5%, 4%, 3%, or 2% of the diameterof the writing electrode 408. In another aspect of this embodiment, thethickness, T, of the writing electrode 408 may cause the midpoint, XM,of the projection to substantially overlap with the point, XL. Inaccordance with this aspect, the thickness, T, may cause the midpoint,XM, to be within a distance from the point, XL, that is 1%, 0.5%, or0.25% of the diameter of the writing electrode 408.

In another aspect of this embodiment, a projection of the first pivotpoint on the sensor matrix 428 is referred to as a first projectedpoint. The first projected point may be a first distance from themidpoint, XM, of the projection of the writing electrode 408 on thesensor matrix 428. The first projected point may be a second distancefrom a projection of the point, XL, on the sensor matrix 428. Thewriting electrode 408 may be configured to cause the first distance tobe less than or equal to the second distance. For instance, thethickness, T, of the writing electrode 408 may be configured such thatthe first distance remains less than or equal to the second distance asthe member 440 is rotated (e.g., about the first pivot point) from thefirst position in which the member 440 is orthogonal to the sensormatrix 428 to the second position in which the member 440 isnon-orthogonal to the sensor matrix 428 (e.g., at least up to an angle,θ, of 30 degrees, 45 degrees, 60 degrees, or 75 degrees).

In a second example embodiment, the thickness, T, of the writingelectrode 408 is configured to cause a location of the writing electrode408 that is detected by the sensor matrix 428 (a.k.a. the “detectedlocation”), XD, to track the point, XL, on the writing electrode 408that is closest to the sensor matrix 428 as member 440 is rotated from afirst position in which the member 440 is orthogonal to the sensormatrix 428 to a second position in which the member 440 isnon-orthogonal to the sensor matrix 428. For instance, the detectedlocation, XD, may track the point, XL, as the member 440 is rotatedabout the first pivot point, which is defined as the point on thewriting electrode 408 that is closest to the sensor matrix 428 when themember 440 is in the first position.

In one aspect of this embodiment, the thickness, T, of the writingelectrode 408 may cause the detected location, XD, to approximatelycoincide with the point, XL. For example, the thickness, T, may causethe detected location, XD, to be within a distance from the point, XL,that is a designated percentage of a diameter of the writing electrode408 in a plane that is perpendicular to the axis 438. In accordance withthis example, the thickness, T, may cause the detected location, XD, tobe within a distance from the point, XL, that is 5%, 4%, 3%, or 2% ofthe diameter of the writing electrode 408. In another aspect of thisembodiment, the thickness, T, of the writing electrode 408 may cause thedetected location, XD, to substantially overlap with the point, XL. Inaccordance with this aspect, the thickness, T, may cause the detectedlocation, XD, to be within a distance from the point, XL, that is 1%,0.5%, or 0.25% of the diameter of the writing electrode 408.

In another aspect of this embodiment, a projection of the detectedlocation on the sensor matrix 428 is referred to as a projected detectedlocation. The first projected point, which is the projection of thefirst pivot point on the sensor matrix 428, may be a first distance fromthe projected detected location. The first projected point may be asecond distance from the projection of the point, XL, on the sensormatrix 428. The writing electrode 408 may be configured to cause thefirst distance to be less than or equal to the second distance. Forinstance, the thickness, T, of the writing electrode 408 may beconfigured such that the first distance remains less than or equal tothe second distance as the member 440 is rotated (e.g., about the firstpivot point) from the first position in which the member 440 isorthogonal to the sensor matrix 428 to the second position in which themember 440 is non-orthogonal to the sensor matrix 428 (e.g., at least upto an angle, θ, of 30 degrees, 45 degrees, 60 degrees, or 75 degrees).

The thickness, T, of the writing electrode 408 may be any suitablethickness. For example, the thickness, T, may be configured to begreater than or equal to 3 mm, greater than or equal to 3.5 mm, greaterthan or equal to 4 mm, greater than or equal to 5 mm, greater than orequal to 6 mm, or greater than or equal to 7 mm. In another example, thethickness, T, may be configured to be greater than or equal to 30%, 40%,50%, 60%, 70%, 80%, or 90% of a width, W, of writing electrode 408 in aplane that is perpendicular to the axis 438. In yet another example, thethickness, T, may be approximately equal to the width, W. In accordancewith this example, a difference between the thickness, T, and the width,W, may be less than or equal to 10%, 5%, 3%, 2%, 1%, 0.5%, 0.25%, 0.1%,or 0.05% of the width, W. In still another example, the differencebetween the thickness, T, and the width, W, may be less than or equal to15%, 20%, 30%, 40%, 50%, or 60% of the width, W. In yet another example,the difference between the thickness, T, and the width, W, may be lessthan or equal to 0.05 mm, 0.1 mm, 0.15 mm, 0.2 mm, 0.5 mm, 1.0 mm, 2.0mm, 3.0 mm, 4.0 mm, or 5.0 mm. In another example, the thickness, T, maybe less than or equal to the width, W. In yet another example, thethickness, T, may be within a specified percentage (e.g., 5%, 20%, 50%,or 100%) greater than the width, W. In still another example, thethickness, T, may be less than or equal to 105%, 120%, 150%, or 200% ofthe width, W. The thickness, T, may be selected from a plurality ofpotential thicknesses to facilitate tracking, though the scope of theexample embodiments is not limited in this respect.

The writing electrode 408 may have any suitable shape. For example, thewriting electrode 408 may be configured to have a cylindrical shape thatextends along the axis 438 and that has a diameter in a plane that isperpendicular to the axis 438. In another example, the writing electrode408 may be configured to have a hemispherical shape. For instance, thehemispherical shape may cause the writing electrode 408 to appearsymmetrical to the sensor matrix 428 regardless of whether the angle, θ,between the orthogonal axis 436 and the axis 438 is zero or non-zero(e.g., greater than or equal to 30 degrees, greater than or equal to 45degrees, or greater than or equal to 70 degrees). In yet anotherexample, the writing electrode 408 may be configured to have a conicalfrustum shape. For instance, the conical frustum shape may have arelatively smaller diameter at a first location along the axis 438 and arelatively larger diameter at a second location along the axis 438,where the first location is a first distance from the distal end, D, ofthe member 440 and the second location is a second distance from thedistal end, D, of the member 440. The first distance may be greater thanthe second distance. In still another example, the writing electrode 408may be configured to have a mitered edge along a surface of the writingelectrode 408 that is farthest from the distal end, D, of the member440.

In yet another example, a cross-sectional area of the writing electrode408 increases from a first cross-sectional area in a first plane that isperpendicular to the axis 438 and that includes a first point on theaxis 438 to a second cross-sectional area in a second plane that isperpendicular to the axis 438 and that includes a second point on theaxis 438. In accordance with this example, the first point is a firstdistance from the distal end, D, of the member 440, and the second pointis a second distance from the distal end, D, of the member 440. Infurther accordance with this example, the first distance is greater thanthe second distance.

FIG. 5 is a diagram of another example device 500 in accordance with anembodiment. The device 500 includes a member 540 and an eraser electrode508. The member 540 has a proximal end, P, and a distal end, D, whichare at opposing ends of an axis 538. The member 540 may be a rigid bodythat contains circuitry for controlling erasing functionality of thedevice 500, though the scope of the example embodiments is not limitedin this respect. The member 540 may have a size and/or a shape of aconventional writing pen or a conventional mechanical eraser, though thescope of the example embodiments is not limited in this respect. Forinstance, the member 540 may be approximately 150 mm long andapproximately 10 mm in diameter or a different size and/or shape.

The eraser electrode 508 is positioned at the distal end, D, of themember 540. The eraser electrode 508 is configured to provide an erasesignal to a sensor matrix of a computing device in response to theeraser electrode 508 being placed proximate the sensor matrix. Thesensor matrix is represented by a line 528 for purposes of illustration.The eraser electrode 508 has a thickness, T, along the axis 538.

As shown in FIG. 5, an orthogonal axis 536 is orthogonal to the sensormatrix 528. Accordingly, the member 540 is orthogonal to the sensormatrix 528 when an angle, θ, between the orthogonal axis 536 and theaxis 538 is zero. The member 540 is non-orthogonal to the sensor matrix528 when the angle, θ, between the orthogonal axis 536 and the axis 538is non-zero (e.g., greater than zero or less than zero).

A projection of the eraser electrode 508 on the sensor matrix 528extends along the line 528 between points X1 and X2. A midpoint of theprojection of the eraser electrode 508 on the sensor matrix 528 isrepresented by point XM. The midpoint, XM, is equidistant between thepoints X1 and X2. A point on the eraser electrode 508 that is closest tothe sensor matrix 528 is represented by point XL.

In a first example embodiment, the thickness, T, of the eraser electrode508 is configured to cause the midpoint, XM, of the projection of theeraser electrode 508 on the sensor matrix 528 to track the point, XL, onthe eraser electrode 508 that is closest to the sensor matrix 528 asmember 540 is rotated from a first position in which the member 540 isorthogonal to the sensor matrix 528 to a second position in which themember 540 is non-orthogonal to the sensor matrix 528. For instance, themidpoint, XM, may track the point, XL, as the member 540 is rotatedabout a second pivot point, which is defined as a point on the eraserelectrode 508 that is closest to the sensor matrix 528 when the member540 is in the first position. It should be noted that the angle, θ, ischanging during the rotation of the member 540 from the first positionto the second position.

In one aspect of this embodiment, the thickness, T, of the eraserelectrode 508 may cause the midpoint, XM, of the projection toapproximately coincide with the point, XL. For example, the thickness,T, may cause the midpoint, XM, to be within a distance from the point,XL, that is a designated percentage of a diameter of the eraserelectrode 508 in a plane that is perpendicular to the axis 538. Inaccordance with this example, the thickness, T, may cause the midpoint,XM, to be within a distance from the point, XL, that is 5%, 4%, 3%, or2% of the diameter of the eraser electrode 508. In another aspect ofthis embodiment, the thickness, T, of the eraser electrode 508 may causethe midpoint, XM, of the projection to substantially overlap with thepoint, XL. In accordance with this aspect, the thickness, T, may causethe midpoint, XM, to be within a distance from the point, XL, that is1%, 0.5%, or 0.25% of the diameter of the eraser electrode 508.

In another aspect of this embodiment, a projection of the second pivotpoint, which is defined as the point on the eraser electrode 508 that isclosest to the sensor matrix 528 when the member 540 is in the firstposition, on the sensor matrix 528 is referred to as a second projectedpoint. The second projected point may be a first distance from themidpoint, XM, of the projection of the eraser electrode 508 on thesensor matrix 528. The second projected point may be a second distancefrom a projection of the point, XL, on the sensor matrix 528. The eraserelectrode 508 may be configured to cause the first distance to be lessthan or equal to the second distance. For instance, the thickness, T, ofthe eraser electrode 508 may be configured such that the first distanceremains less than or equal to the second distance as the member 540 isrotated (e.g., about the second pivot point) from the first position inwhich the member 540 is orthogonal to the sensor matrix 528 to thesecond position in which the member 540 is non-orthogonal to the sensormatrix 528 (e.g., at least up to an angle, θ, of 30 degrees, 45 degrees,60 degrees, or 75 degrees).

In a second example embodiment, the thickness, T, of the eraserelectrode 508 is configured to cause a location of the eraser electrode508 that is detected by the sensor matrix 528 (a.k.a. the “detectedlocation”), XD, to track the point, XL, on the eraser electrode 508 thatis closest to the sensor matrix 528 as the member 540 is rotated from afirst position in which the member 540 is orthogonal to the sensormatrix 528 to a second position in which the member 540 isnon-orthogonal to the sensor matrix 528. For instance, the detectedlocation, XD, may track the point, XL, as the member 540 is rotatedabout the second pivot point, which is defined as the point on theeraser electrode 508 that is closest to the sensor matrix 528 when themember 540 is in the first position.

In one aspect of this embodiment, the thickness, T, of the eraserelectrode 508 may cause the detected location, XD, to approximatelycoincide with the point, XL. For example, the thickness, T, may causethe detected location, XD, to be within a distance from the point, XL,that is a designated percentage of a diameter of the eraser electrode508 in a plane that is perpendicular to the axis 538. In accordance withthis example, the thickness, T, may cause the detected location, XD, tobe within a distance from the point, XL, that is 5%, 4%, 3%, or 2% ofthe diameter of the eraser electrode 508. In another aspect of thisembodiment, the thickness, T, of the eraser electrode 508 may cause thedetected location, XD, to substantially overlap with the point, XL. Inaccordance with this aspect, the thickness, T, may cause the detectedlocation, XD, to be within a distance from the point, XL, that is 1%,0.5%, or 0.25% of the diameter of the eraser electrode 508.

In another aspect of this embodiment, a projection of the detectedlocation on the sensor matrix 528 is referred to as a projected detectedlocation. The second projected point, which is the projection of thesecond pivot point on the sensor matrix 528, may be a first distancefrom the projected detected location. The second projected point may bea second distance from the projection of the point, XL, on the sensormatrix 528. The eraser electrode 508 may be configured to cause thefirst distance to be less than or equal to the second distance. Forinstance, the thickness, T, of the eraser electrode 508 may beconfigured such that the first distance remains less than or equal tothe second distance as the member 540 is rotated (e.g., about the secondpivot point) from the first position in which the member 540 isorthogonal to the sensor matrix 528 to the second position in which themember 540 is non-orthogonal to the sensor matrix 528 (e.g., at least upto an angle, θ, of 30 degrees, 45 degrees, 60 degrees, or 75 degrees).

The thickness, T, of the eraser electrode 508 may be any suitablethickness. For example, the thickness, T, may be configured to begreater than or equal to 3 mm, greater than or equal to 3.5 mm, greaterthan or equal to 4 mm, greater than or equal to 5 mm, greater than orequal to 6 mm, or greater than or equal to 7 mm. In another example, thethickness, T, may be configured to be greater than or equal to 30%, 40%,50%, 60%, 70%, 80%, or 90% of a width, W, of the eraser electrode 508 ina plane that is perpendicular to the axis 538. In yet another example,the thickness, T, may be approximately equal to the width, W. Inaccordance with this example, a difference between the thickness, T, andthe width, W, may be less than or equal to 10%, 5%, 3%, 2%, 1%, 0.5%,0.25%, 0.1%, or 0.05% of the width, W. In still another example, thedifference between the thickness, T, and the width, W, may be less thanor equal to 15%, 20%, 30%, 40%, 50%, or 60% of the width, W. In yetanother example, the difference between the thickness, T, and the width,W, may be less than or equal to 0.05 mm, 0.1 mm, 0.15 mm, 0.2 mm, 0.5mm, 1.0 mm, 2.0 mm, 3.0 mm, 4.0 mm, or 5.0 mm. In another example, thethickness, T, may be less than or equal to the width, W. In yet anotherexample, the thickness, T, may be within a specified percentage (e.g.,5%, 20%, 50%, or 100%) greater than the width, W. In still anotherexample, the thickness, T, may be less than or equal to 105%, 120%,150%, or 200% of the width, W. The thickness, T, may be selected from aplurality of potential thicknesses to facilitate tracking, though thescope of the example embodiments is not limited in this respect.

The eraser electrode 508 may have any suitable shape. For example, theeraser electrode 508 may be configured to have a cylindrical shape thatextends along the axis 538 and that has a diameter in a plane that isperpendicular to the axis 538. In another example, the eraser electrode508 may be configured to have a hemispherical shape. For instance, thehemispherical shape may cause the eraser electrode 508 to appearsymmetrical to the sensor matrix 528 regardless of whether the angle, θ,between the orthogonal axis 536 and the axis 538 is zero or non-zero(e.g., greater than or equal to 30 degrees, greater than or equal to 45degrees, or greater than or equal to 70 degrees). In yet anotherexample, the eraser electrode 508 may be configured to have a conicalfrustum shape. For instance, the conical frustum shape may have arelatively smaller diameter at a first location along the axis 538 and arelatively larger diameter at a second location along the axis 538,where the first location is a first distance from the proximal end, P,of the member 540 and the second location is a second distance from theproximal end, P, of the member 540. The first distance may be greaterthan the second distance. In still another example, the eraser electrode508 may be configured to have a mitered edge along a surface of theeraser electrode 508 that is farthest from the proximal end, P, of themember 540.

In yet another example, a cross-sectional area of the eraser electrode508 increases from a first cross-sectional area in a first plane that isperpendicular to the axis 538 and that includes a first point on theaxis 538 to a second cross-sectional area in a second plane that isperpendicular to the axis 538 and that includes a second point on theaxis 538. In accordance with this example, the first point is a firstdistance from the proximal end, P, of the member 540, and the secondpoint is a second distance from the proximal end, P, of the member 540.In further accordance with this example, the first distance is greaterthan the second distance.

FIG. 6 is a diagram of yet another example device 600 in accordance withan embodiment. The device 600 includes a member 640, a writing electrode608A, and an eraser electrode 608B. The member 640 has a proximal end,P, and a distal end, D, which are at opposing ends of an axis 638. Themember 640 may be a rigid body that contains circuitry for controllingwriting functionality and erasing functionality of the device 600,though the scope of the example embodiments is not limited in thisrespect.

The writing electrode 608A is positioned at the proximal end, P, of themember 640. The writing electrode 608A has a first thickness, T1, alongthe axis 638. The writing electrode 608A is configured to provide awrite signal to a sensor matrix of a computing device in response to thewriting electrode 608A being placed proximate the sensor matrix.

The eraser electrode 608B is positioned at the distal end, D, of themember 640. The eraser electrode 608B has a second thickness, T2, alongthe axis 538. The eraser electrode 608B is configured to provide anerase signal to the sensor matrix in response to the eraser electrode608B being placed proximate the sensor matrix.

FIG. 7 is a diagram of still another example device 700 in accordancewith an embodiment. The device 700 includes an elongated member 740, amodule 742, and a driver circuit 744. The elongated member 740 extendsalong an axis 738. The elongated member 740 may at least partiallysurround the module 742 and the driver circuit 744, as shown in FIG. 7,though the example embodiments are not limited in this respect. Thedriver circuit 744 is configured to generate an active signal. Forinstance, the driver circuit 744 may drive the active signal fortransmission from the device 700 while the device 700 is capacitivelycoupled to a sensor matrix of a computing device, which is representedby line 728. The module 742, which is coupled to an end of the elongatedmember 740, includes an electrode 708 that is configured to provide theactive signal electrostatically to the sensor matrix 728. For instance,the electrode 708 may provide the active signal in response to theelectrode 708 being placed proximate the sensor matrix 728. Theelectrode 708 has a thickness, T, along the axis 738.

In FIG. 7, the device 700 is shown to have an eraser configuration forillustrative purposes. In the eraser configuration, the module 742 iscoupled to a distal end, D, of the elongated member 740, and theelectrode 708 is an eraser electrode. In the eraser configuration, theactive signal is an erase signal. Accordingly, the driver circuit 744may be configured to generate the active signal to initiate an erasureoperation with respect to content displayed by the computing device. Theelectrode 708 may be configured to provide the active signalelectrostatically in accordance with the erasure operation. For example,the erasure operation may be configured to cause an erasure to occur ata location on a display of the computing device that corresponds to alocation of the module 742 or the electrode 708 that is detected by thesensor matrix 728. In another example, the erasure operation may beconfigured to cause an erasure to occur at a location on the display ofthe computing device that corresponds to a point on the elongated member740 that is closest to the sensor matrix 728.

It will be recognized that the device 700 may have a writingconfiguration, rather than an eraser configuration. In the writingconfiguration, the module 742 is coupled to a proximal end, P, of theelongated member 740, rather than the distal end, D. In the writingconfiguration, the electrode 708 is a writing electrode, and the activesignal is a write signal. Accordingly, the driver circuit 744 may beconfigured to generate the active signal to initiate a write operationto provide writing on a display of the computing device. The electrode708 may be configured to provide the active signal electrostatically inaccordance with the write operation. For example, the write operationmay be configured to cause writing to occur at a location on the displayof the computing device that corresponds to the location of the module742 or the electrode 708 that is detected by the sensor matrix 728. Inanother example, the write operation may be configured to cause writingto occur at a location on the display of the computing device thatcorresponds to the point on the elongated member 740 that is closest tothe sensor matrix 728.

As shown in FIG. 7, an orthogonal axis 736 is orthogonal to the sensormatrix 728, which is represented by the line 728. Accordingly, themember 740 is orthogonal to the sensor matrix 28 when an angle, θ,between the orthogonal axis 736 and the axis 738 is zero. The member 740is non-orthogonal to the sensor matrix 728 when the angle, θ, betweenthe orthogonal axis 736 and the axis 738 is non-zero (e.g., greater thanzero or less than zero).

A projection of the electrode 708 on the sensor matrix 728 extends alongthe line 728 between points X1 and X2. A midpoint of the projection ofthe electrode 708 on the sensor matrix 728 is represented by point XM.The midpoint, XM, is equidistant between the points X1 and X2. A pointon the electrode 708 that is closest to the sensor matrix 728 isrepresented by point XL.

In a first example implementation of the device 700, the thickness, T,of the electrode 708 is configured to cause the midpoint, XM, of theprojection of the electrode 708 on the sensor matrix 728 to track thepoint, XL, on the electrode 708 that is closest to the sensor matrix 728as the elongated member 740 is rotated from a first position in whichthe elongated member 740 is orthogonal to the sensor matrix 728 to asecond position in which the elongated member 740 is non-orthogonal tothe sensor matrix 728. For instance, the midpoint, XM, may track thepoint, XL, as the elongated member 740 is rotated about a third pivotpoint, which is defined as a point on the electrode 708 that is closestto the sensor matrix 728 when the elongated member 740 is in the firstposition. It should be noted that the angle, θ, is changing during therotation of the elongated member 740 from the first position to thesecond position.

In one aspect of this implementation, the thickness, T, of the electrode708 may cause the midpoint, XM, of the projection to approximatelycoincide with the point, XL. For example, the thickness, T, may causethe midpoint, XM, to be within a distance from the point, XL, that is adesignated percentage of a diameter of the electrode 708 in a plane thatis perpendicular to the axis 738. In accordance with this example, thethickness, T, may cause the midpoint, XM, to be within a distance fromthe point, XL, that is 5%, 4%, 3%, or 2% of the diameter of electrode708. In another aspect of this embodiment, the thickness, T, of theelectrode 708 may cause the midpoint, XM, of the projection tosubstantially overlap with the point, XL. In accordance with thisaspect, the thickness, T, may cause the midpoint, XM, to be within adistance from the point, XL, that is 1%, 0.5%, or 0.25% of the diameterof the electrode 708.

In another aspect of this embodiment, a projection of the third pivotpoint, which is defined as the point on the electrode 708 that isclosest to the sensor matrix 728 when the elongated member 740 is in thefirst position, on the sensor matrix 728 is referred to as a thirdprojected point. The third projected point may be a first distance fromthe midpoint, XM, of the projection of the electrode 708 on the sensormatrix 728. The third projected point may be a second distance from aprojection of the point, XL, on the sensor matrix 728. The electrode 708may be configured to cause the first distance to be less than or equalto the second distance. For instance, the thickness, T, of the electrode708 may be configured such that the first distance remains less than orequal to the second distance as the elongated member 740 is rotated(e.g., about the third pivot point) from the first position in which theelongated member 740 is orthogonal to the sensor matrix 728 to thesecond position in which the elongated member 740 is non-orthogonal tothe sensor matrix 728 (e.g., at least up to an angle, θ, of 30 degrees,45 degrees, 60 degrees, or 75 degrees).

In a second example implementation of the device 700, the thickness, T,of the electrode 708 is configured to cause a location of the module 742or the electrode 708 that is detected by the sensor matrix 728 (a.k.a.the “detected location”), XD, to track the point, XL, on the electrode708 that is closest to the sensor matrix 728 as the elongated member 740is rotated from a first position in which the elongated member 708 isorthogonal to the sensor matrix 728 to a second position in which theelongated member 708 is non-orthogonal to the sensor matrix 728. Forinstance, the detected location, XD, may track the point, XL, as theelongated member 740 is rotated about the third pivot point, which isdefined as the point on the electrode 708 that is closest to the sensormatrix 728 when the elongated member 740 is in the first position.

In one aspect of this implementation, the thickness, T, of the electrode708 may cause the detected location, XD, to approximately coincide withthe point, XL. For example, the thickness, T, may cause the detectedlocation, XD, to be within a distance from the point, XL, that is adesignated percentage of a diameter of the electrode 708 in a plane thatis perpendicular to the axis 738. In accordance with this example, thethickness, T, may cause the detected location, XD, to be within adistance from the point, XL, that is 5%, 4%, 3%, or 2% of the diameterof the electrode 708. In another aspect of this embodiment, thethickness, T, of the electrode 708 may cause the detected location, XD,to substantially overlap with the point, XL. In accordance with thisaspect, the thickness, T, may cause the detected location, XD, to bewithin a distance from the point, XL, that is 1%, 0.5%, or 0.25% of thediameter of the electrode 708.

In another aspect of this embodiment, a projection of the detectedlocation on the sensor matrix 728 is referred to as a projected detectedlocation. The third projected point, which is the projection of thethird pivot point on the sensor matrix 728, may be a first distance fromthe projected detected location. The third projected point may be asecond distance from the projection of the point, XL, on the sensormatrix 728. The electrode 708 may be configured to cause the firstdistance to be less than or equal to the second distance. For instance,the thickness, T, of the electrode 708 may be configured such that thefirst distance remains less than or equal to the second distance as theelongated member 740 is rotated (e.g., about the third pivot point) fromthe first position in which the elongated member 740 is orthogonal tothe sensor matrix 728 to the second position in which the elongatedmember 740 is non-orthogonal to the sensor matrix 728 (e.g., at least upto an angle, θ, of 30 degrees, 45 degrees, 60 degrees, or 75 degrees).

The thickness, T, of the electrode 708 may be any suitable thickness,and the electrode 708 may have any suitable shape, as described abovewith reference to the writing electrode 408 and the eraser electrode 508in respective FIGS. 4 and 5.

Any one or more of the devices 104, 204, 400, 500, 600, and/or 700 maybe implemented as an electrostatic pen. Any one or more of the devices104, 204, 400, 500, and/or 600 may be implemented as a passive pen.

III. Further Discussion of Some Example Embodiments

A first example device includes a member, a first electrode, and asecond electrode. The member has a proximal end and a distal end atopposing ends of an axis. The first electrode is positioned at theproximal end. The first electrode is configured to provide a writesignal to a sensor matrix of a computing device in response to the firstelectrode being placed proximate the sensor matrix. The second electrodeis positioned at the distal end. The second electrode is configured toprovide an erase signal to the sensor matrix of the computing device inresponse to the second electrode being placed proximate the sensormatrix. The second electrode has a thickness along the axis. Thethickness is configured to cause a midpoint of a projection of thesecond electrode on the sensor matrix to track a point on the secondelectrode that is closest to the sensor matrix as the member is rotatedfrom a first position in which the member is orthogonal to the sensormatrix to a second position in which the member is non-orthogonal to thesensor matrix.

In a first aspect of the first example device, the first example devicefurther comprises a driver circuit configured to generate the erasesignal. In accordance with the first aspect, the erase signal is anactive signal. In further accordance with the first aspect, the secondelectrode is configured to provide the erase signal electrostatically tothe sensor matrix in response to the second electrode being placedproximate the sensor matrix.

In a second aspect of the first example device, the thickness isconfigured to cause the midpoint of the projection to track the point onthe second electrode that is closest to the sensor matrix as the memberis rotated about a pivot point from the first position to the secondposition. In accordance with the second aspect, the pivot point isdefined as a point on the second electrode that is closest to the sensormatrix when the member is in the first position. The second aspect ofthe first example device may be implemented in combination with thefirst aspect of the first example device, though the example embodimentsare not limited in this respect.

In a third aspect of the first example device, the thickness isconfigured to be approximately equal to a width of the second electrodein a plane that is perpendicular to the axis. The third aspect of thefirst example device may be implemented in combination with the firstand/or second aspect of the first example device, though the exampleembodiments are not limited in this respect.

In a fourth aspect of the first example device, the thickness isconfigured to be greater than or equal to three millimeters. The fourthaspect of the first example device may be implemented in combinationwith the first, second, and/or third aspect of the first example device,though the example embodiments are not limited in this respect.

In a fifth aspect of the first example device, a cross-sectional area ofthe second electrode increases from a first cross-sectional area in afirst plane that is perpendicular to the axis and that includes a firstpoint on the axis to a second cross-sectional area in a second planethat is perpendicular to the axis and that includes a second point onthe axis. In accordance with the fifth aspect, the first point is afirst distance from the proximal end. In further accordance with thefifth aspect, the second point is a second distance from the proximalend. In further accordance with the fifth aspect, the first distance isgreater than the second distance. The fifth aspect of the first exampledevice may be implemented in combination with the first, second, third,and/or fourth aspect of the first example device, though the exampleembodiments are not limited in this respect.

In a sixth aspect of the first example device, the thickness isconfigured to cause the midpoint of the projection of the secondelectrode on the sensor matrix to track the point on the secondelectrode that is closest to the sensor matrix as the member is rotatedabout a pivot point from the first position to the second position. Inaccordance with the sixth aspect, the pivot point is defined to be apoint on the second electrode that is closest to the sensor matrix whenthe member is in the first position. In further accordance with thesixth aspect, a projection of the pivot point on the sensor matrix is afirst distance from the midpoint of the projection of the secondelectrode on the sensor matrix. In further accordance with the sixthaspect, the projection of the pivot point on the sensor matrix is asecond distance from the point on the second electrode that is closestto the sensor matrix. In further accordance with the sixth aspect, thethickness is configured to cause the first distance to remain less thanor equal to the second distance as the member is rotated about the pivotpoint from the first position to the second position. The sixth aspectof the first example device may be implemented in combination with thefirst, second, third, fourth, and/or fifth aspect of the first exampledevice, though the example embodiments are not limited in this respect.

In a seventh aspect of the first example device, the second electrode isconfigured to have a shape of a conical frustum. The seventh aspect ofthe first example device may be implemented in combination with thefirst, second, third, fourth, fifth, and/or sixth aspect of the firstexample device, though the example embodiments are not limited in thisrespect.

In an eighth aspect of the first example device, the second electrode isconfigured to be a passive slug. The eighth aspect of the first exampledevice may be implemented in combination with the first, second, third,fourth, fifth, sixth, and/or seventh aspect of the first example device,though the example embodiments are not limited in this respect.

A second example device includes a member and an electrode. The memberhas a proximal end and a distal end at opposing ends of an axis. Theelectrode is positioned at a designated end of the member. Thedesignated end is the proximal end or the distal end. The electrode isconfigured to provide a signal to a sensor matrix of a computing devicein response to the electrode being placed proximate the sensor matrix.The electrode has a thickness along the axis. The thickness isconfigured to cause a location of the electrode that is detected by thesensor matrix to track a point on the electrode that is closest to thesensor matrix as the member is rotated from a first position in whichthe member is orthogonal to the sensor matrix to a second position inwhich the member is non-orthogonal to the sensor matrix.

In a first aspect of the second example device, the second exampledevice further includes a driver circuit configured to generate thesignal. In accordance with the first aspect, the signal is an activesignal. In further accordance with the first aspect, the electrode isconfigured to provide the signal electrostatically to the sensor matrixin response to the electrode being placed proximate the sensor matrix.

In a second aspect of the second example device, the electrode isconfigured to be a passive slug. The second aspect of the second exampledevice may be implemented in combination with the first aspect of thesecond example device, though the example embodiments are not limited inthis respect.

In a third aspect of the second example device, the thickness isconfigured to be approximately equal to a width of the electrode in aplane that is perpendicular to the axis. The third aspect of the secondexample device may be implemented in combination with the first and/orsecond aspect of the second example device, though the exampleembodiments are not limited in this respect.

In a fourth aspect of the second example device, the thickness isconfigured to be greater than or equal to thirty percent of a width ofthe electrode in a plane that is perpendicular to the axis. The fourthaspect of the second example device may be implemented in combinationwith the first, second, and/or third aspect of the second exampledevice, though the example embodiments are not limited in this respect.

In a fifth aspect of the second example device, the electrode isconfigured to have a shape of a hemisphere. The fifth aspect of thesecond example device may be implemented in combination with the first,second, third, and/or fourth aspect of the second example device, thoughthe example embodiments are not limited in this respect.

In a sixth aspect of the second example device, a cross-sectional areaof the electrode increases from a first cross-sectional area in a firstplane that is perpendicular to the axis and that includes a first pointon the axis to a second cross-sectional area in a second plane that isperpendicular to the axis and that includes a second point on the axis.In accordance with the sixth aspect, the first point is a first distancefrom a specified end of the member. In further accordance with the sixthaspect, the specified end is the proximal end or the distal end that isnot the designated end. In further accordance with the sixth aspect, thesecond point is a second distance from the specified end. In furtheraccordance with the sixth aspect, the first distance is greater than thesecond distance. The sixth aspect of the second example device may beimplemented in combination with the first, second, third, fourth, and/orfifth aspect of the second example device, though the exampleembodiments are not limited in this respect.

In a seventh aspect of the second example device, the electrode isconfigured to have a shape of a conical frustum. The seventh aspect ofthe second example device may be implemented in combination with thefirst, second, third, fourth, fifth, and/or sixth aspect of the secondexample device, though the example embodiments are not limited in thisrespect.

In an eighth aspect of the second example device, the thickness isconfigured to cause the location of the electrode that is detected bythe sensor matrix to track the point on the electrode that is closest tothe sensor matrix as the member is rotated about a pivot point from thefirst position to the second position. In accordance with the eighthaspect, the pivot point is defined as a point on the electrode that isclosest to the sensor matrix when the member is in the first position.The eighth aspect of the second example device may be implemented incombination with the first, second, third, fourth, fifth, sixth, and/orseventh aspect of the second example device, though the exampleembodiments are not limited in this respect.

In a ninth aspect of the second example device, the thickness isconfigured to cause the location of the electrode that is detected bythe sensor matrix to track the point on the electrode that is closest tothe sensor matrix as the member is rotated about a pivot point from thefirst position to the second position. In accordance with the ninthaspect, the pivot point is defined to be a point on the electrode thatis closest to the sensor matrix when the member is in the firstposition. In further accordance with the ninth aspect, a projection ofthe pivot point on the sensor matrix is a first distance from aprojection of the location of the electrode that is detected by thesensor matrix on the sensor matrix. In further accordance with the ninthaspect, the projection of the pivot point on the sensor matrix is asecond distance from the point on the electrode that is closest to thesensor matrix. In further accordance with the ninth aspect, thethickness is configured to cause the first distance to remain less thanor equal to the second distance as the member is rotated about the pivotpoint from the first position to the second position. The ninth aspectof the second example device may be implemented in combination with thefirst, second, third, fourth, fifth, sixth, seventh, and/or eighthaspect of the second example device, though the example embodiments arenot limited in this respect.

A third example device includes an elongated member, a driver circuit,and a module. The elongated member extends along an axis. The drivercircuit is configured to generate an active signal. The module iscoupled to an end of the elongated member. The module includes anelectrode that is configured to provide the active signalelectrostatically to a sensor matrix of a computing device. Theelectrode has a thickness along the axis. The thickness is configured tocause a midpoint of a projection of the electrode on the sensor matrixto track a point on the electrode that is closest to the sensor matrixas the elongated member is rotated from a first position in which theelongated member is orthogonal to the sensor matrix to a second positionin which the elongated member is non-orthogonal to the sensor matrix.

In a first aspect of the third example device, the thickness isconfigured to be approximately equal to a width of the electrode in aplane that is perpendicular to the axis.

In a second aspect of the third example device, the thickness isconfigured to be greater than or equal to fifty percent of a width ofthe electrode in a plane that is perpendicular to the axis. The secondaspect of the third example device may be implemented in combinationwith the first aspect of the third example device, though the exampleembodiments are not limited in this respect.

In a third aspect of the third example device, the elongated memberextends along the axis between the end to which the module is coupledand a second end. In accordance with the third aspect, a cross-sectionalarea of the electrode increases from a first cross-sectional area in afirst plane that is perpendicular to the axis and that includes a firstpoint on the axis to a second cross-sectional area in a second planethat is perpendicular to the axis and that includes a second point onthe axis. In further accordance with the third aspect, the first pointis a first distance from the second end of the elongated member. Infurther accordance with the third aspect, the second point is a seconddistance from the second end of the elongated member. In furtheraccordance with the third aspect, the first distance is greater than thesecond distance. The third aspect of the third example device may beimplemented in combination with the first and/or second aspect of thethird example device, though the example embodiments are not limited inthis respect.

In a fourth aspect of the third example device, the driver circuit isconfigured to generate the active signal to initiate an erasureoperation with respect to content displayed by the computing device. Inaccordance with the fourth aspect, the electrode is configured toprovide the active signal electrostatically in accordance with theerasure operation. The fourth aspect of the third example device may beimplemented in combination with the first, second, and/or third aspectof the third example device, though the example embodiments are notlimited in this respect.

In a fifth aspect of the third example device, the driver circuit isconfigured to generate the active signal to initiate a write operationto provide writing on a display of the computing device. In accordancewith the fifth aspect, the electrode is configured to provide the activesignal electrostatically in accordance with the write operation. Thefifth aspect of the third example device may be implemented incombination with the first, second, third, and/or fourth aspect of thethird example device, though the example embodiments are not limited inthis respect.

In a sixth aspect of the third example device, the thickness isconfigured to cause the midpoint of the projection to track the point onthe electrode that is closest to the sensor matrix as the elongatedmember is rotated about a pivot point from the first position to thesecond position. In accordance with the sixth aspect, the pivot point isdefined as a point on the electrode that is closest to the sensor matrixwhen the elongated member is in the first position. The sixth aspect ofthe third example device may be implemented in combination with thefirst, second, third, fourth, and/or fifth aspect of the third exampledevice, though the example embodiments are not limited in this respect.

In a seventh aspect of the third example device, the electrode isconfigured to have a shape of a hemisphere. The seventh aspect of thethird example device may be implemented in combination with the first,second, third, fourth, fifth, and/or sixth aspect of the third exampledevice, though the example embodiments are not limited in this respect.

In an eighth aspect of the third example device, the electrode isconfigured to have a shape of a conical frustum. The eighth aspect ofthe third example device may be implemented in combination with thefirst, second, third, fourth, fifth, sixth, and/or seventh aspect of thethird example device, though the example embodiments are not limited inthis respect.

In a ninth aspect of the third example device, the thickness isconfigured to cause the midpoint of the projection of the electrode onthe sensor matrix to track the point on the electrode that is closest tothe sensor matrix as the elongated member is rotated about a pivot pointfrom the first position to the second position. In accordance with theninth aspect, the pivot point is defined to be a point on the electrodethat is closest to the sensor matrix when the elongated member is in thefirst position. In further accordance with the ninth aspect, aprojection of the pivot point on the sensor matrix is a first distancefrom the midpoint of the projection of the electrode on the sensormatrix. In further accordance with the ninth aspect, the projection ofthe pivot point on the sensor matrix is a second distance from the pointon the electrode that is closest to the sensor matrix. In furtheraccordance with the ninth aspect, the thickness is configured to causethe first distance to remain less than or equal to the second distanceas the elongated member is rotated about the pivot point from the firstposition to the second position. The ninth aspect of the third exampledevice may be implemented in combination with the first, second, third,fourth, fifth, sixth, seventh, and/or eighth aspect of the third exampledevice, though the example embodiments are not limited in this respect.

IV. CONCLUSION

Although the subject matter has been described in language specific tostructural features and/or acts, it is to be understood that the subjectmatter defined in the appended claims is not necessarily limited to thespecific features or acts described above. Rather, the specific featuresand acts described above are disclosed as examples of implementing theclaims, and other equivalent features and acts are intended to be withinthe scope of the claims.

What is claimed is:
 1. A device comprising: a member having a proximalend and a distal end at opposing ends of an axis; a first electrodepositioned at the proximal end, the first electrode configured toprovide a write signal to a sensor matrix of a computing device inresponse to the first electrode being placed proximate the sensormatrix; and a second electrode positioned at the distal end, the secondelectrode configured to provide an erase signal to the sensor matrix ofthe computing device in response to the second electrode being placedproximate the sensor matrix, the second electrode having a thicknessalong the axis, the thickness configured to cause a midpoint of aprojection of the second electrode on the sensor matrix to track a pointon the second electrode that is closest to the sensor matrix as themember is rotated from a first position in which the member isorthogonal to the sensor matrix to a second position in which the memberis non-orthogonal to the sensor matrix.
 2. The device of claim 1,further comprising: a driver circuit configured to generate the erasesignal; wherein the erase signal is an active signal; and wherein thesecond electrode is configured to provide the erase signalelectrostatically to the sensor matrix in response to the secondelectrode being placed proximate the sensor matrix.
 3. The device ofclaim 1, wherein the thickness is configured to cause the midpoint ofthe projection to track the point on the second electrode that isclosest to the sensor matrix as the member is rotated about a pivotpoint from the first position to the second position, the pivot pointdefined as a point on the second electrode that is closest to the sensormatrix when the member is in the first position.
 4. The device of claim1, wherein the thickness is configured to be approximately equal to awidth of the second electrode in a plane that is perpendicular to theaxis.
 5. The device of claim 1, wherein the thickness is configured tobe greater than or equal to three millimeters.
 6. The device of claim 1,wherein a cross-sectional area of the second electrode increases from afirst cross-sectional area in a first plane that is perpendicular to theaxis and that includes a first point on the axis to a secondcross-sectional area in a second plane that is perpendicular to the axisand that includes a second point on the axis; wherein the first point isa first distance from the proximal end; wherein the second point is asecond distance from the proximal end; and wherein the first distance isgreater than the second distance.
 7. A device comprising: a memberhaving a proximal end and a distal end at opposing ends of an axis; andan electrode positioned at a designated end of the member, thedesignated end being the proximal end or the distal end, the electrodeconfigured to provide a signal to a sensor matrix of a computing devicein response to the electrode being placed proximate the sensor matrix,the electrode having a thickness along the axis, the thicknessconfigured to cause a location of the electrode that is detected by thesensor matrix to track a point on the electrode that is closest to thesensor matrix as the member is rotated from a first position in whichthe member is orthogonal to the sensor matrix to a second position inwhich the member is non-orthogonal to the sensor matrix.
 8. The deviceof claim 7, further comprising: a driver circuit configured to generatethe signal; wherein the signal is an active signal; and wherein theelectrode is configured to provide the signal electrostatically to thesensor matrix in response to the electrode being placed proximate thesensor matrix.
 9. The device of claim 7, wherein the electrode isconfigured to be a passive slug.
 10. The device of claim 7, wherein thethickness is configured to be approximately equal to a width of theelectrode in a plane that is perpendicular to the axis.
 11. The deviceof claim 7, wherein the thickness is configured to be greater than orequal to thirty percent of a width of the electrode in a plane that isperpendicular to the axis.
 12. The device of claim 7, wherein thethickness is configured to cause the location of the electrode that isdetected by the sensor matrix to track the point on the electrode thatis closest to the sensor matrix as the member is rotated about a pivotpoint from the first position to the second position; wherein the pivotpoint is defined to be a point on the electrode that is closest to thesensor matrix when the member is in the first position; wherein aprojection of the pivot point on the sensor matrix is a first distancefrom a projection of the location of the electrode that is detected bythe sensor matrix on the sensor matrix; wherein the projection of thepivot point on the sensor matrix is a second distance from the point onthe electrode that is closest to the sensor matrix; and wherein thethickness is configured to cause the first distance to remain less thanor equal to the second distance as the member is rotated about the pivotpoint from the first position to the second position.
 13. The device ofclaim 7, wherein a cross-sectional area of the electrode increases froma first cross-sectional area in a first plane that is perpendicular tothe axis and that includes a first point on the axis to a secondcross-sectional area in a second plane that is perpendicular to the axisand that includes a second point on the axis; wherein the first point isa first distance from a specified end of the member, the specified endbeing the proximal end or the distal end that is not the designated end;wherein the second point is a second distance from the specified end;and wherein the first distance is greater than the second distance. 14.The device of claim 13, wherein the electrode is configure to have ashape of a conical frustum.
 15. A device comprising: an elongated memberthat extends along an axis; a driver circuit configured to generate anactive signal; and a module coupled to an end of the elongated member,the module including an electrode that is configured to provide theactive signal electrostatically to a sensor matrix of a computingdevice, the electrode having a thickness along the axis, the thicknessconfigured to cause a midpoint of a projection of the electrode on thesensor matrix to track a point on the electrode that is closest to thesensor matrix as the elongated member is rotated from a first positionin which the elongated member is orthogonal to the sensor matrix to asecond position in which the elongated member is non-orthogonal to thesensor matrix.
 16. The device of claim 15, wherein the thickness isconfigured to be approximately equal to a width of the electrode in aplane that is perpendicular to the axis.
 17. The device of claim 15,wherein the thickness is configured to be greater than or equal to fiftypercent of a width of the electrode in a plane that is perpendicular tothe axis.
 18. The device of claim 15, wherein the elongated memberextends along the axis between the end to which the module is coupledand a second end; wherein a cross-sectional area of the electrodeincreases from a first cross-sectional area in a first plane that isperpendicular to the axis and that includes a first point on the axis toa second cross-sectional area in a second plane that is perpendicular tothe axis and that includes a second point on the axis; wherein the firstpoint is a first distance from the second end of the elongated member;wherein the second point is a second distance from the second end of theelongated member; and wherein the first distance is greater than thesecond distance.
 19. The device of claim 15, wherein the driver circuitis configured to generate the active signal to initiate an erasureoperation with respect to content displayed by the computing device; andwherein the electrode is configured to provide the active signalelectrostatically in accordance with the erasure operation.
 20. Thedevice of claim 15, wherein the driver circuit is configured to generatethe active signal to initiate a write operation to provide writing on adisplay of the computing device; and wherein the electrode is configuredto provide the active signal electrostatically in accordance with thewrite operation.